(57) The truck includes two parallel damper ramp supports connected together by a transverse tie assembly. A single wheeled axle is pivotally supported from the damper ramp supports in spaced apart parallel alignment with the transverse tie assembly by two independently sprung and damped radius arms. A swivel assembly is mounted by the transverse tie assembly in overlying relation with the axle. Two yaw control assemblies respectively act between the damper ramp supports and an overhead railcar body. Each of the yaw control assemblies includes a yaw damper that provides either a damping force or both a damping force and a self-centering force in response to rotative movement of the truck. A railcar equipped with two such trucks also is disclosed.